ARM: sunxi: common-regulators: Drop pinmux settings for GPIO pins

As part of our effort to move pinctrl/GPIO interlocking into the
driver where it belongs, this patch drops the definition and usage
of the pinmux settings for the common regulators defined in
sunxi-common-regulators.dtsi.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>